Sansanee Jamjod

Genotypic variation in plant response to low boron and implications for plant breeding

Plant response to low B in the soil varies widely among species, and among genotypes within a species. Boron efficient genotypes are those that are able to grow well in soils in which other genotypes are adversely affected by B deficiency. This review considers the extent of variation in B efficiency in plant species and genotypes, the physiological nature of the efficiency mechanisms, what is known of the genetic basis for inheritance, screening techniques and the practical implications of the genotypic variations.Frequently, B efficiency is the sole reason for a difference between an average yield and complete crop failure. Severe yield losses can be effectively prevented by the inclusion of B efficiency as a selection criterion in crop breeding and improvement programmes for regions with low B soils. In addition, the expression of B deficiency primarily through male sterility, which is common in many species, creates opportunities for outcrossing in normally self-fertilised species. This, in turn, leads to two possibilities. Firstly, self fertilisation, and therefore maintenance of pure lines, cannot always be assumed in self pollinated species where B efficient and inefficient genotypes are grown side by side on low B soils. Secondly, B deficiency, in soil or artificial media, may be used as a fertility selective medium in which the male sterile B inefficient genotypes and the male fertile B efficient genotypes could hybridise naturally. This would be useful as a simple and economical method for creating heterozygous populations in breeding programmes as well as for producing hybrid seeds. Now that the roles of B in plant growth and development are beginning to be clarified, the efficiency mechanisms as well as the governing genetics can be explained. Practical benefits from the genetic diversity of B efficiency will be enhanced by a better understanding of B efficiency mechanisms and the molecular bases for their genetic control.

Nitrogen Fertilizer Increases Seed Protein and Milling Quality of Rice

ABSTRACT Rice grain breakage during milling is a problem in many parts of Asia. It has been suggested that nitrogen (N) fertilizer can improve the milling quality of rice. Therefore, this study investigates effects of N fertilization on grain N concentration, endosperm storage protein distribution, and milling quality of rice. Four Thai extra long grain commercial rice cultivars (KDML105, KLG1, PTT1, and CNT1) were grown at Chiang Mai University in the wet season of 2001 with 0 or 120 kg of N/ha at flowering. Anatomical sections showed that there was more storage protein accumulated in the lateral regions of polished grain of high N concentration than in grain of low N concentration. Percent (%) unbroken rice was positively correlated with relative abundance of storage protein in the lateral region of the endosperm in all cultivars. Applying N increased head rice N concentration in all cultivars, whereas % unbroken rice was increased in KLG1 and CNT1. KDML105 cultivar, on the other hand, already had high ...

Boron deficiency induced male sterility in wheat (Triticum aestivum L.) and implications for plant breeding

Boron (B) deficiency causes grain set in wheat to fail. A wide range of genotypic variation in the response to low B has been observed. Genotypes were screened in low B in soil and sand culture, and classified into five groups, namely, very sensitive, sensitive, moderately sensitive, moderately tolerant and tolerant. At very low levels of B, the very sensitive to sensitive genotypes were completely male sterile and set only a few or no grain, while the tolerant genotypes set grain normally. Natural outcrossing was detected in these male sterile plants when a tolerant genotype was growing nearby. Grain set by cross fertilisation was markedly enhanced by a B application directly on the ear of the male sterile plants. Three practical implications are suggested. Firstly, genotypes that are tolerant to low B can provide a solution for grain set failure caused by B deficiency. Secondly, the potential for outcrossing in male sterile B deficient wheat has to be taken into account in the maintenance of pure lines in low B soils even though wheat is normally self pollinated. Thirdly, a simple and novel method for hybridization is suggested, in which B deficiency is used as fertility selective medium and male sterile female parents and fertile male parents are provided by genotypic variation in the response to low B.

Genotypic variation in response of barley to boron deficiency

Responses of a range of barley (Hordeum vulgare L.) genotypes to boron (B) deficiency were studied in two experiments carried out in sand culture and in the field at Chiang Mai, Thailand. In experiment 1, two barley genotypes, Stirling (two-row) and BRB 2 (six-row) and one wheat (Triticum aestivum L.) genotype, SW 41, were evaluated in sand culture with three levels of applied B (0, 0.1 and 1.0 μM B) to the nutrient solution. It was found that B deficiency depressed flag leaf B concentration at booting, grain number and grain yield of all genotypes. In barley Stirling, B deficiency also depressed number of spikes plant-1, spikelets spike-1 and straw yield. However, no significant difference between genotypes in flag leaf B concentration was found under low B treatments. Flag leaf B concentration below 4 mg kg-1 was associated with grain set reduction and could, therefore, be used as a general indicator for B status in barley. In experiment 2, nine barley and two wheat genotypes were evaluated in the field on a low B soil with three levels of B. Boron levels were varied by applying either 2 t of lime ha-1 (BL), no B (B0) or 10 kg Borax ha-1 (B+) to the soil prior to sowing. Genotypes differed in their B response for grain spike-1, grain spikelet-1 and grain set index (GSI). The GSI of the B efficient wheat, Fang 60, exceeded 90% in all B treatments. The B inefficient wheat SW 41 and most of the barley genotypes set grain normally (GSI >80%) only at the B+. In B0 GSI of the barley genotypes ranged from 23% to 84%, and in BL from 19% to 65%. Three of the barley with severely depressed GSI in B0 and BL also had a decreased number of spikelets spike-1. In experiment 3, 21 advanced barley lines from the Barley Thailand Yield Nursery 1997/98 (BTYN 1997/98) were screened for B response in sand culture with no added B. Grain Set Index of the Fang 60 and SW 41 checks were 98 and 65%, respectively, and GSI of barley lines ranged between 5 and 90%. One advanced line was identified as B efficient and two as moderately B efficient. The remaining lines ranked between moderately inefficient to inefficient. These experiments have established that there is a range of responses to B in barley genotypes. This variation in the B response was observed in vegetative as well as reproductive growth. Boron efficiency should be considered in breeding and selection of barley in low B soils.

Genetic control of boron efficiency in wheat (Triticum aestivum L.)

The genetic control of boron (B) efficiencyin wheat (Triticum aestivum L.) wasstudied for three genotypes representing Binefficient (I, Bonza), moderately Binefficient (MI, SW 41) and B efficient (E,Fang 60) categories. Boron efficiency wasexpressed as a partially dominant characterbut the phenotypes of F1 hybrids,relative to parents, indicated geneticcontrol varying from recessive to additiveto completely dominant with different crosscombinations and B levels. Major geneswere identified from the evaluation ofF2-derived F3 populations derivedfrom intercrosses between the threeparents. Monogenic segregation was foundin Bonza × SW 41 and SW 41 × Fang 60crosses and digenic segregation resultedin Bonza × Fang 60. Among thethree wheat genotypes with widely differentB efficiency, genetic variation forresponse to B could be accounted for by twogenes, Bod1 and Bod2.

Effect of grain morphology on degree of milling and iron loss in rice

ABSTRACT Grain morphological characteristics were thought to play a significant role in genotypic variation in Fe concentration in white rice. Comparing 17 rice cultivars representing six major grain morphological categories, the present study systematically investigated the relationship between grain morphology, the degree of milling (DOM), and the loss of Fe during the polishing process. The relative importance of key morphological parameters in this relationship was also investigated. The grain morphological characteristics of different rice cultivars significantly affected the degree of Fe loss during polishing to produce white rice. This variation in Fe loss from polishing among the six categories of rice cultivars is mainly due to their difference in DOM (r = 0.73**) and this loss in Fe was the primary factor determining the level of Fe concentration in the white rice. Among the morphological parameters investigated, grain length and length-to-width ratios played the most significant role in determi...

Complexity and adaptability of a traditional agricultural system: case study of a gall midge resistant rice landrace from northern Thailand

Adaptability of traditional agricultural systems is suggested by their success over time, but documentation of how this happens is rare. This paper shows how genetic diversity in a rice landrace enables rice farming system of northern Thailand to adapt to a constraint of an insect pest, microenvironments of mountainous landscape and people’s different tastes in rice. Resistance to laboratory-reared gall midge varied among accessions the rice landrace Muey Nawng and gall midge populations. Higher rice yield in farmers’ fields reflected adaptation to local environment as well as resistance to gall midge. Microsatellite variation of the accessions correlated negatively with their gall midge resistance, but there was also variation in heading time and endosperm starch. Presence of non-waxy endosperm in glutinous rice provides opportunity to select for rice that is cooked into non-glutinous rice preferred by minority groups who live at higher elevations, where the gall midge is emerging as a new threat, possibly because of climate change. These data show how genetic diversity of a rice landrace coupled with seed management by farmers enabled a rice farming system to adapt to the varied microenvironment of a mountainous landscape under the constraint of an insect pest and people’s different tastes in rice.

Overcoming wheat sterility problem with boron efficiency

Grain set failure, due to boron (B) deficiency-induced sterility of the anthers and pollen, is a cause of yield loss in many wheat growing areas of Asia. This paper illustrates a range of genotypic variation in the response to B that can be found in the wheat germplasm, and offers a solution in selection and breeding for boron efficiency.

Boron Efficiency in a Wheat Germplasm from Bangladesh

Wheat production in Bangladesh has grown from about 32,000 tons from 60,000 ha in 1961 to almost 2 million tons from 800,000 ha by the year 2000. Wheat has contributed significantly to the country’s food security. Bangladesh wheat crop, however, often suffers from the problem of grain set failure. Boron (B) deficiency has been identified as one major cause of this problem. Soils on which wheat is grown in Bangladesh commonly contain 0.1−0.3 mg hot water soluble B kg−1 (HWS B), at which B deficiency has been shown to cause grain set failure through male sterility (Li et al 1978; Rerkasem and Loneragan 1994). On the other hand, wheat genotypes have been shown to respond differently to low B (Rerkasem and Jamjod, 1997). This study evaluated a set of wheat varieties and advanced breeding lines from Bangladesh national breeding program to assess their response to B in two experiments conducted at Chiang Mai University, Thailand.

Comparison of BOR1-like gene expression in two genotypes with different boron efficiencies in commercial crop plants in Thailand

Abstract In Thailand, boron (B) deficiency in soil is found in the north region where wheat (Triticum aestivum L.), maize (Zea mays L.) and rice (Oryza sativa L.) are promoted cereals. Physiological analysis and genetic variation in B efficiency among plant genotypes have been reported; however, the molecular and genetic mechanisms of low B tolerance remain unclear. In this present study, we investigated the molecular basis of low B tolerance in wheat, maize and rice. Transcript levels of BOR1-like genes, efflux-type B transporters, were compared between B-efficient and B-inefficient genotypes in different organs using quantitative real-time polymerase chain reaction (PCR). The results revealed that the transcript levels of BOR1-like genes are differential between two different genotypes. We found the tendency that transcripts of BOR1-like gene are accumulated to higher levels in B deficiency tolerant cultivar than the sensitive ones in most tested tissues. It is possible that the expression levels of BOR1-like genes are correlated with the B deficiency tolerance in plants. Moreover, BOR1-like genes can be useful as gene expression biomarkers for crop breeding in wheat, maize and rice by selecting appropriate tissues and growth stages.