Shuna Yuan

A novel NAP member GhNAP is involved in leaf senescence in Gossypium hirsutum

Highlight GhNAP could regulate leaf senescence via the ABA-mediated pathways and is related to the yield and quality of cotton.

Molecular Evolution and Expansion Analysis of the NAC Transcription Factor in Zea mays

NAC (NAM, ATAF1, 2 and CUC2) family is a plant-specific transcription factor and it controls various plant developmental processes. In the current study, 124 NAC members were identified in Zea mays and were phylogenetically clustered into 13 distinct subfamilies. The whole genome duplication (WGD), especially an additional WGD event, may lead to expanding ZmNAC members. Different subfamily has different expansion rate, and NAC subfamily preference was found during the expansion in maize. Moreover, the duplication events might occur after the divergence of the lineages of Z. mays and S. italica, and segmental duplication seemed to be the dominant pattern for the gene duplication in maize. Furthermore, the expansion of ZmNAC members may be also related to gain and loss of introns. Besides, the restriction of functional divergence was discovered after most of the gene duplication events. These results could provide novel insights into molecular evolution and expansion analysis of NAC family in maize, and advance the NAC researches in other plants, especially polyploid plants.

Improvements of Fertility Restoration in Cytoplasmic Male Sterile Cotton by Enhanced Expression of Glutathione S-Transferase (GST) Gene

The molecular and biochemical bases of fertility restoration were explored using cytoplasmic male sterile (CMS) Ji A, maintainer Ji B, and two cotton hybrids RF1 and QF1, developed by crossing CMS with DES-HAF277 (normal restorer) and Zheda strong restorer (transgenic restorer with GST gene), respectively. Transcript levels of both exogenous and endogenous GST genes were high in anther as compared to other plant tissues of the QF1 hybrid. Moreover, the expression of the GST gene during meiosis (stage 2) and microspore development (stage 3) was highest in the QF1 hybrid. The ratio of cyanide-resistant respiration to total respiration was also high in the QF1 hybrid during stage 2 and stage 3 as compared to the RF1 hybrid. O2− and H2O2 contents increased more during stage 2 in the CMS line and stage 3 in the RF1 hybrid compared to the maintainer and QF1 hybrid. Similarly, MDA contents were at a maximum in CMS followed by the RF1, QF1, and the maintainer line during the whole course of anther development. In addition, the activities of antioxidant enzymes (SOD, POD, CAT, APX, GST, GR, and DHAR) and contents of non-enzymatic antioxidants (GSH and ASA) were elevated in the QF1 hybrid as compared to the RF1 hybrid, during the whole course of anther development. The present study suggests that the introgression of the GST gene into restorer lines could be a potential way to enhance restoration capability by maintaining the equilibrium between oxidative stress and scavenging enzymes, and might favor healthier development of microspores.

Molecular evolution and species-specific expansion of the NAP members in plants

The NAP (NAC-Like, Activated by AP3 /PI) subfamily is one of the important plant-specific transcription factors, and controls many vital biological processes in plants. In the current study, 197 NAP proteins were identified from 31 vascular plants, but no NAP members were found in eight non-vascular plants. All NAP proteins were phylogenetically classified into two groups (NAP I and NAP II), and the origin time of the NAP I group might be relatively later than that of the NAP II group. Furthermore, species-specific gene duplications, caused by segmental duplication events, resulted in the expansion of the NAP subfamily after species-divergence. Different groups have different expansion rates, and the NAP group preference was found during the expansion in plants. Moreover, the expansion of NAP proteins may be related to the gain and loss of introns. Besides, functional divergence was limited after the gene duplication. Abscisic acid (ABA) might play an important role in leaf senescence, which is regulated by NAP subfamily. These results could lay an important foundation for expansion and evolutionary analysis of NAP subfamily in plants.

In vitro inhibition of pigmentation and fiber development in colored cotton

Colored cotton has naturally pigmented fibers. The mechanism of pigmentation in cotton fiber is not well documented. This experiment was conducted to study the effects of respiratory chain inhibitors, i.e., rotenone and thiourea, on pigmentation and fiber development in colored cotton. After 1 d post-anthesis, ovaries were harvested and developing ovules were cultured on the liquid medium containing different concentrations of rotenone and thiourea for 30 d. The results demonstrate that both respiratory inhibitors reduced fiber length and ovule development under ovule culture conditions, and the inhibition efficiency of rotenone was much higher than that of thiourea. Rotenone and thiourea also showed significant effects on fiber pigment (color) development in colored cotton. In green cotton fiber, rotenone advanced fiber pigment development by 7 d at 200 μmol/L, while thiourea inhibited fiber pigmentation at all treatment levels (400, 600, 800, 1 000, and 2 000 μmol/L). Both respiratory inhibitors, however, had no significant effects on pigmentation of brown cotton fibers. The activities of cytochrome c oxidase (COX) and polyphenol oxidase (PPO) decreased significantly with increasing levels of both respiratory inhibitors. It is suggested that both respiratory inhibitors have important roles in deciphering the mechanism of pigmentation and fiber development in colored cotton.

Expression of alfalfa antifungal peptide gene and enhance of resistance to Verticillium dahliae in upland cotton

Abstract In order to increase cotton plant resistance to Verticillium dahliae (V. dahliae), an alfalfa antifungal peptide gene (alfAFP), directed by CaMV35S promoter in recombinant binary vector pCAMBIA1301-alf, was delivered into an upland cotton cultivar 5983 (Gossypium hirsutum L.) via an Agrobacterium-mediated hypocotyl system. Molecular analysis confirmed the integration and transcripts of the alfAFP gene in the genome of 12 transformants. In vitro assays showed that crude leaf extracts from transformants was able to significantly (p<0.01) inhibit the growth and proliferation of V. dahliae compared to the extracts from control plants. In vivo assays with fungal pathogens showed that transformants displayed a significant reduction in their disease symptoms compared to control plants. These results suggest that the alfAFP gene was expressed in the upland cotton and its product of gene expression was active in the growth inhibition of V. dahliae.