The Effect of Fruit Bearing on Low-molecular-weight Metabolites in Stems of Satsuma Mandarin (<i>Citrus unshiu</i> Marc.)

Abstract

In citrus, fruit bearing affects floral induction and the nutritional condition of the tree. For this reason, bearing too many or too few fruit causes fluctuation in flower number the following spring. This in turn leads to annual alternation between rich and poor crops, known as alternate bearing. To identify the metabolites related to alternate bearing, quantitative metabolomics analysis was conducted with stem tissues of vegetative shoots collected in November. Twelve Satsuma mandarin trees bearing different amounts of fruit were used in this study. Fruit weight per leaf area of these trees was significantly and negatively correlated with the expression of a flowering-related gene, citrus FLOWERING LOCUS T, in the stem in November and the number of flower buds the following spring. In metabolomics analysis, adenosine triphosphate was detected at high concentrations in lightly fruiting trees. Other coenzymes such as uridine triphosphate, nicotinamide adenine dinucleotide phosphate, and ascorbic acid were also more abundant in the off-crop trees. In addition, the off-crop trees accumulated sugar phosphates such as fructose 6-phosphate, glucose 6-phosphate, and ribulose 1,5-diphosphate. Furthermore, heavily fruiting trees accumulated more amino acids. These results indicate that fruit bearing affects the metabolism of coenzymes, sugars, and amino acids in the stem of vegetative shoots.

Predicting the Number of Flowers in Satsuma Mandarin (<i>Citrus unshiu</i> Marc.) Trees Based on Citrus <i>FLOWERING LOCUS T</i> mRNA Levels

“…2A, B, see all markers without distinction). As we previously reported (Nishikawa, 2013;Nishikawa et al, 2012Nishikawa et al, , 2016, trees with low CiFT mRNA levels in November bore few flowers the following spring, while trees in which CiFT was highly expressed produced more flowers. The relationship between CiFT mRNA level and number of flowers per 100 nodes showed an exponential pattern.…”

“…Fruit production is also a factor that suppresses floral induction. In citrus trees, CiFT expression levels in the fall and winter are negatively correlated with the number of fruits produced, but positively correlated with the number of flowers the following spring (Nishikawa, 2013;Nishikawa et al, 2012Nishikawa et al, , 2016. Furthermore, CiFT expression and floral induction are enhanced by drought stress (Chica and Alberigo, 2013), and suppressed by gibberellin treatment (GoldbergMoeller et al, 2013;Muñoz-Fambuena et al, 2012).…”

Climate variables effect on fruiting pattern of Kinnow mandarin (Citrus nobilis Lour × C. deliciosa Tenora) grown at different agro-climatic regions

“…In certain fruit crops, including citrus, a cyclical carry-over effects of previous year's fruit present on trees are dominantly competed for carbohydrate reserves 45 and/ or trigger phyto-inhibiting effects on next season's floral bud-break/ initiation 50 can stimulate irregular fruiting patterns, commonly called as biennial bearing 38 while on-tree fruits influence on plant metabolism, like changes in coenzymes, sugars and amino acids, which are being accelerated when fruits are harvested late 49 . Similar findings of late harvesting in avocado induce biennial bearing with reduced fruit yields 106 .…”

“…In addition, heavy fruit-load plants source (leaves) photoassimilates are more streamlined towards fruits 43 which has depleted carbohydrates to the rest of the plant parts including aerial (shoots & leaves) and ground (roots) to induce low floral bud induction for the coming season 44 is typically seen in citrus 45 , avocado 46 , olive 47 and mango 48 . Fruit-load specifically disrupts amino acids, coenzymes and sugars 49 and also the phyto-inhibiting effect on incoming flowers 50 to stimulate uneven fruiting patterns 38 . Heavy fruiting during on-year leave cyclical carry-over effects that minimize carbohydrates 51 and also string inhibitory effect of phytohormones on flowering during the off-year period 50 by endorsing nutritional and hormonal aspects on citrus with annual fruiting pattern 52 , 53 .…”

Influence of varying environmental conditions on biennial bearing habit of Kinnow fruit (Citrus nobilis Lour x C. deliciosa Tenora) grown at different clusters in the Punjab province, Pakistan

“…As harvesting was delayed, more biennial bearing was seen in these districts as compared to Sargodha where timely harvesting retard this phenomena. Fruit bearing affects plant metabolic processes involving coenzymes, sugars and amino acids (Nishikawa et al, 2016) and late harvesting accelerated it and affected next season crop. Late harvesting in both Vehari and TTS during heavy bearing crop resulted in low crop in next year and timely harvesting in Sargodha has reduced effect of alternate bearing.…”