Abstract
Sugarcane is a significant crop plant with the capability of accumulating higher amount of sucrose. In the present study, a high sucrose content sugarcane mutant clone, GXB9, has been studied in comparison to the low sucrose mother clone B9 on morphological, agronomical and physiological level in order to scrutinize the variation because of mutation in GXB9 in field under normal environmental condition. The results showed that GXB9 has less germination, tillering rate, stalk height, leaf length, leaf width, leaf area, number of internodes, internode length and internode diameter than B9. Qualitative traits of leaf and stalk displayed significant variation between GXB9 and B9. Endogenous hormones quantity was also showed variation between the two clones. The relative SPAD reading and chlorophyll a, b concentrations also showed variation between GXB9 and B9. The photosynthetic parameter analysis indicated that the GXB9 has significantly higher net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) than B9. The qRT-PCR analysis of genes encoding enzymes like SPS, SuSy, CWIN, and CeS showed upregulation in GXB9 and downregulation in B9. However, these genes were significantly differentially expressed between the immature and maturing internodes of GXB9. The cane quality trait analysis showed that GXB9 had higher juice rate, juice gravity purity, brix, juice sucrose content and cane sucrose content than B9. The yield and component investigation results indicated that GXB9 had lower single stalk weight, however higher number of millable stalks per hectare than B9, and GXB9 had lower theoretical cane yield than B9. SSR marker analysis showed genetic variation between GXB9 and B9. This study has shown significant variation in the traits of GXB9 in comparison to B9 which advocates that GXB9 is a high sugar mutant clone of B9 and an elite source for future breeding.
Highlights
Sugarcane (Saccharum spp. hybrid) is an important sugar and bioenergy crop because of its capability for high sucrose content accumulation in stalks; in ripen internodes [1–3]
At the last of germination stage, it was noticed that there were some heart-leaf withered plants, which were caused by borer damage, and the situation was severer in Guixuan B9 (GXB9) than B9 (Fig 1)
Higher expression of sucrose phosphate synthase (SPS) is linked with higher quantity of sucrose in the mature internodes while lower level of SPS expression is connected with lower sucrose in the immature internodes, which is in agreement with the results reported by [85], but inconsistent to the results observed by [86, 87] who reported immature internodes have higher SPS activity than mature internodes
Summary
Sugarcane (Saccharum spp. hybrid) is an important sugar and bioenergy crop because of its capability for high sucrose content accumulation in stalks; in ripen internodes [1–3]. Sugarcane is a C4 photosynthetic plant with good competence to use the resources, and gives efficient production of products sucrose [4–7]. The sugarcane growth cycle passes through different phases, including germination phase, tillering phase, grand growth phase, maturity and ripening phase from planting to harvesting. Sugarcane plants are perennial, whose stalks can be several meters in length having juicy with higher concentrations of sucrose. Sugarcane root system consists of adventitious and permanent shoot root types. Sugarcane leaves, which consist of leaf blade and sheath, are numbered from top to bottom starting with the uppermost leaf showing a visible dewlap designated as leaf +1 (2). Leaf traits including the shape, size, distribution of trichomes, shape of the ligule and auricles are of taxonomic importance for varietal identification [10]
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