Plant roots are highly plastic to high salinity. However, the molecular mechanism by which root developmental plasticity is regulated remains largely unknown. Previously we reported that miR172c-NNC1 module plays a key role in soybean-rhizobial symbiosis. The fact that the miR172c promoter contains several stress-related cis elements indicates that miR172c may have a role in root response to abiotic stress. Here we showed that miR172c is greatly induced by salt stress in soybean. Overexpression of miR172c and knockdown of miR172c activity resulted in substantially increased and reduced root sensitivity to salt stress, respectively. Furthermore, we show that the target gene NNC1 (Nodule Number Control 1) of miR172c was downregulated by salt stress. The transgenic roots overexpressing or knocking down NNC1 expression also exhibited the altered root sensitivity to salt stress. The study reveals the crucial role of miR172c-NNC1 module in root stress tolerance to salt stress in soybean.

In the present study, genetic linkage analysis was carried out to map the fiber color loci Lc ₁ and Lc ₂ on two brown cotton cultivars with SSR and EST-SSR markers in the reference map by F₂ segregation populations. The Lc ₁ locus carried by Xincaimian6 (Gossypium hirsutum L.) was flanked by the marker NAU2862 and NAU1043 on the long arm of Chromosome 07, with genetic distance 7.8 cM and 3.8 cM, respectively. The Lc ₂ carried by Xincaimian 5 (Gossypium hirsutum L.) was flanked by the marker NAU5433 and NAU2968 on the short arm of Chromosome 06, with genetic distance 4.4 cM and 7.4 cM respectively. Moreover, the marker NAU3735 and marker NAU5434 co-segregated with the Lc ₁ and the Lc ₂ locus, respectively. The results of marker association studies with these two loci provides the basic information for the final isolation of these important genes in colored cotton, and these linkage markers also could facilitate application of marker assisted selection in the future.

Nodulation is the most efficient nitrate assimilation system in the ecosystem while excessive fertilization increased nitrate inhibition effect, deciphering the nitrate signal transduction mechanism in the process is of the utmost importance. In this study, genome-wide analysis of the GmCEP genes were applied to identify nodulation related CEPgenes, 22 GmCEP family members were identified while GmCEP6 mainly expressed in nodule and significantly responded to nitrate treatment and rhizobium infection, especially in later stages. Overexpression and CRISPR-Cas9 were used to validate its role in nodulation. We found GmCEP6overexpression significantly increased the nodule number while GmCEP6knock out significantly decreased nodule number suggests GmCEP6 function as a positive regulator in soybean nodulation. qRT-PCR shown that alterations in the expression of GmCEP6 affected the expression of marker genes in the Nod factor signaling pathway. Lastly the function of GmCEP6 in nitrate inhibition of nodulation was analyzed, nodule number in the GmCEP6 overexpressed roots significantly increased under nitrogen treatments suggests GmCEP6 functions in resistance to nitrate inhibition. The study will help us understand that GmCEP6 promotes nodulation and participates in the regulation of nitrate inhibition of nodulation, which is of great significance for high efficiency utilization of nitrogen in soybean.