The CaCA superfamily genes in Saccharum: comparative analysis and their functional implications in response to biotic and abiotic stress.

BACKGROUND: In plants, Calcium (Ca2+) acts as a universal messenger in various signal transduction pathways, including responses to biotic and abiotic stresses and regulation of cellular and developmental processes. The Ca2+/cation antiporter (CaCA) superfamily proteins play vital roles in the transport of Ca2+ and/or other cations. However, the characteristics of these superfamily members in Saccharum and their evolutionary and functional implications have remained unclear. RESULTS: A total of 34 CaCA genes in Saccharum spontaneum, 5 CaCA genes in Saccharum spp. R570, and 14 CaCA genes in Sorghum bicolor were identified and characterized. These genes consisted of the H+/cation exchanger (CAX), cation/Ca2+ exchanger (CCX), EF-hand / CAX (EFCAX), and Mg2+/H+ exchanger (MHX) families, among which the CCX and EFCAX could be classified into three groups while the CAX could be divided into two groups. The exon/intron structures and motif compositions suggested that the members in the same group were highly conserved. Synteny analysis of CaCAs established their orthologous and paralogous relationships among the superfamily in S. spontaneum, R570, and S. bicolor. The results of protein-protein interactions indicated that these CaCA proteins had direct or indirect interactions. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis demonstrated that most members of Saccharum CaCA genes exhibited a similar expression pattern in response to hormonal (abscisic acid, ABA) treatment but played various roles in response to biotic (Sporisorium scitamineum) and abiotic (cold) stresses. Furthermore, ScCAX4, a gene encoding a cytoplasm, plasma membrane and nucleus positioning protein, was isolated from sugarcane. This gene was constitutively expressed in different sugarcane tissues and its expression was only induced at 3 and 6 h time points after ABA treatment, however was inhibited and indued in the whole process under cold and S. scitamineum stresses, respectively. CONCLUSIONS: This study systematically conducted comparative analyses of CaCA superfamily genes among S. spontaneum, R570, and S. bicolor, delineating their sequence and structure characteristics, classification, evolutionary history, and putative functions. These results not only provided rich gene resources for exploring the molecular mechanism of the CaCA superfamily genes but also offered guidance and reference for research on other gene families in Saccharum.

[Effects of zinc and boron nutrition on balsam pear (Momordica charantia) yield and quality, and polyamines, hormone, and senescence of its leaves].

Field trial and physiological determination on the effects of zinc and boron nutrition on balsam pear (Momordica charantia) yield and quality and on polyamines, hormone, and senescence of its leaves showed that application of ZnSO4.7H2O and Na2B4o7.10H2O on Zn and B deficient soils could increase balsam pear yield and its contents of protein, Vc and 17 sorts of amino acids, especially the contents of essential amino acids for human body, but decrease the NO3(-)-N content. The reason was that Zn and B could increase polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm), indole acetic acid (IAA), gibberellic acid (GA3) and ascorbic acid (ASA) contents and superoxide dismutase (SOD), peroxidase (POD) and catalase(CAT) activities, and reduce malondialdehyde (MDA), abscisic acid (ABA) contents in leaves, which inhibited membrane lipid peroxidation. The results also showed that there was a significant positive correlation between yields and PAs, Put, Spd, Spm, GA3, SOD, POD, CAT, but a significant negative correlation with MDA and ABA contents in leaves. There was a significant positive correlation between MDA and ABA, but a significant negative correlation with PAs, Put, Spd, Spm, IAA, GA3, ASA, SOD, POD, and CAT.