Gu Minghong

Variation and distribution of seed storage protein content and composition among different rice varieties.

The crude protein contents(PC) in 351 varieties were measured by near infrared spectroscopy(NIRS) and their distribution and classification were analyzed.The results showed that the average value of crude protein content in indica and japonica types were 13.2% and 12.2%,respectively,with an average of 12.42%.The ranges of those above were 10.8-16.8%,9.3-17.7%,and 9.3-17.7%,respectively.It elucidated that PC was higher in indica rice than that in japonica rice.The huge difference in ratios of varieties(lines) based on their PC showed the genetic disequilibrium between subspecies indica and japonica,for example,the ratio of japonica rice with low PC was eight times that of indica rice with low PC.According to the criterion classifying varieties with different protein contents,most of rice genotypes fell into the group with intermediate PC,and there was very small number of varieties with either high or low PC,especially with very high PC in japonica rice.However,we could find some extreme individuals whose PC were very high/low,such as those with high PC:forage rice,early maturity varieties and indica-japonica hybrid progenies close to indica in the subspecies of indica,or close to japonica in the subspecies of japonica;and those with low PC:some japonica rice(but the PC not low enough),some overseas germplasms in indica.Thus it was not impossible to find out extreme germplasms on PC from landrace,overseas germplasms or indica-japonica hybrid progenies etc.,which are fine basic materials in genetic and breeding research.From the results of SDS-PAGE analysis of the total seed storage proteins among some representative varieties,we could know that the seed storage protein composition was different among different types of rice genotypes.

Comparative study on breeding utilization characteristics of the isonuclear alloplasmic japonica CMS lines Liuqianxin A with four different cytoplasm sources.

A set of isonuclear alloplasmic japonica CMS lines Liuqianxin A,constructed with four different cytoplasm sources from Hainan Male Sterile Wild Rice (WA type),Hainan Red Awned Wild Rice (HL type),Hunan Chaling Wild Rice (CL type),and India Chinsurah Boro II (BT type),respectively,together with their maintainer line Liuqianxin B,were applied to study their male sterile stability,flowering habits,outcrossing rate,and restorable ability.The results showed:(1) Most pollen granules of BT,HL and CL Liuqianxin A were mainly stained-abortion,while those of WA Liuqianxin A were mainly typical-abortion.Selfed seed-setting rate of BT Liuqianxin A was 0.60%,which would cause application risk in agricultural production.There were no selfed seeds in HL and CL Liuqianxin A,indicating that sterility of them was better than that of BT type.(2) The length of 1st internode to the top was affected by the degree of abortive pollen,which influenced the plant height and the panicle exsertion (i.e.the length of panicle-neck above the sheath of flag leaf).Namely the more serious abortive degree,the shorter panicle exsertion.Therefore,panicle was enclosed within the sheath of the flag leaf in WA Liuqianxin A,not in BT,HL,and CL Liuqianxin A.(3) The flowering habits of WA Liuqianxin A presented as sporadic flowering,distinctly lagged flowering time and stretched flowering duration,and were the worst in the four type CMS lines,thus its outcrossing rate was lower.Flowering habits and outcrossing rate between HL,CL CMS lines and BT CMS lines were not significantly different.However it was better in HL,CL CMS lines than in WA CMS lines.(4) BT Liuqianxin A showed the best restorable characteristic,HL was a little worse than BT,WA was the worst.And japonica restorers for HL or CL CMS lines could be selected from the japonica restorers for BT CMS lines.HL,CL CMS lines balanced above contradictions well,so an idea of substituting HL,CL CMS lines partly for BT type was put forward,it can be used to solve the problems of single type sterile cytoplasm in current Japonica hybrid rice and fertility not stable in BT CMS lines.

Milling Characteristics and Distribution of Seed Storage Proteins in Rice with Various Grain Shapes

Rice(Oryza sativa L.),one of the most important crops,is a very good and relatively cheap source of energy and protein.The processing quality and nutrition distribution are different among rice varieties.The objective of the present study was to explore the distribution of proteins in rice kernel and to provide some references on the processing of high-quality rice using three rice cultivars with different quality and grain shapes,including two japonica cultivars Suyunuo and Yangfujing 4901,and one indica rice Qiangluzhan 11.The degree of milling(DOM,0–25%) and milling time were carefully measured,respectively.The results showed that the hardness was increased from outer to inner bran layers,and unchanged in endosperm fractions,which was higher than that of bran layers.This non-linear relationship between milling time and DOM implied variability in hardness within different rice fractions.Furthermore,the analysis of relationship between protein content and DOM indicated that the protein was not equably distributed within the brown rice kernel.The endosperm(DOM 9%) was identified to contain most of the rice kernel proteins(about 85% of total seed proteins) in all the three cultivars.But the protein content in the brown rice kernel decreased from outer to inner fractions,and that in core endosperm fractions was only about half of that in bran layers.In addition,SDS-PAGE analysis for total proteins in the grains with various DOM showed that the distribution of seed protein components was relatively uniform,suggesting the synchro genetic expression of seed protein components in rice grain.

Analysis of Characteristics and Heterosis of Three-Line Parents in Hybrid Japonica Rice

Sixteen representative varieties each for BT-type cytoplasmic-nucleic male sterility (CMS) lines,maintainers and restorers were collected respectively,and 229 hybrid combinations were developed in this study.Then the correlations between parents and progenies were analysed on the all traits.The main results were as follows: (1) Compared with the maintainers,the restorers had higher plant height,thicker stalk and bigger panicle.The latent storage capacity of the maintainers and restorers was about 30 g on an average,and the restorers had less tillers,lower seed setting rate and lower 1000-grain weigh,resulting in the lower yield per plant.The chalkiness degree of restorers was higher than that of maintainers,while the amylose content of restorers was significantly lower than that of maintainers.(2) The mid-parent heterosis of hybrid japonica rice was strong,while the over-parent heterosis of most characters was weak excepting the competitive advantage of growth vigor.The panicles of hybrid japonica rice were big,showing the positive heterosis,but the seed setting rate had a negative heterosis,which was the main limiting factor on the yield heterosis of hybrid japonica rice.(3) Analysis of the correlation between parents and their progenies indicated that the correlation between the character values of F1 combinations and this mid-parent values was the best.Comparatively,the correlations between CMS lines and F1 in heading date and total spikelets per panicle were significant,while the correlations of restorers and F1 in plant height,filled grains per panicle,seed setting rate,yield per plant and quality characters were significant.

Breeding and Field Performance of Novel Soft and Waxy Transgenic Rice Lines Without Selectable Marker

Amylose content is one of the important factors affecting rice cooking and eating quality, and controlled by the Waxy (Wx) gene which encoding a granule-bound starch synthase. High amylose levels are usually associated with poor cooking and eating quality. In our prevrious studies, in order to generate transgenic rice varieties with improved quality and without of the selectable marker, the antisense Wx gene was co-transformed together with a selectable marker gene, the hygromycin-resistant gene (HPT), to a high-yielding japonica rice cultivar, Wuxiangjing 9, mediated with Agrobacterium tumeficien. And some select- able marker-free (SMF) transgenic lines had been subsequently selected. In present study, several homozygous transgenic lines with soft or waxy grain property were selected from the offspring of these SMF transformants containing the antisense Wx gene. The results from Northern blot analysis indicated that the levels of both the Wx mature mRNA and unspliced transcripts were reduced differently in the endosperm of different transgenic lines. The Wx protein level in mature seeds of the transgenic lines was also reduced differently. The amylose content of two transgenic lines was reduced to that of soft rice (about 10%) and one line was reduced to that of waxy rice (lower than 2%). The gel consistency of these transgenic lines was softer than that of the wild type. The variance of gelatination temperature between the transgenic lines and the wild type did not reach to significant level. The most of the main agronomic traits of these transgenic lines were similar to that of the wild type. Therefore, three SMF trans- genic homozygous lines with improved quality were successfully bred.

Molecular mapping of two semidwarf genes in an indica rice variety Aitaiyin3 (Oryza sativa L.)

Genetic analysis established that Aitaiyin3, a dwarf rice variety derived from a semidwarf cultivar Taiyin1, carries two recessive semidwarf genes. By using simple sequence repeat (SSR) markers, we mapped the two semidwarf genes, sd-1 and sd-t2 on chromosomes 1 and 4, respectively. Sd-t2 was thus named because the semidrawf gene sd-t has already been identified from Aitaiyin 2 whose origin could be traced back to Taiyin1. The result of the molecular mapping of sd-1 gene revealed it is linked to four SSR markers found on chromosome 1. These markers are: RM297, RM302, RM212, and OSR3 spaced at 4.7 cM, 0 cM, 0.8cM and 0 cM, respectively. Sd-t2 was found to be located on chromosome 4 using five SSR markers: two markers, SSR332 and RM1305 located proximal to sd-t2 are spaced 11.6 cM, 3.8 cM, respectively, while the three distally located primers, RM5633, RM307, and RM401 are separated by distances of 0.4 cM, 0.0 cM, and 0.4 cM, respectively.