TPI activity levels were lowest in the oldest leaves −4, increased in younger leaves, and the youngest leaves +4 had about 3.6 times more TPI activity than leaves −4 (Additional file 2), confirming that JA-induced TPI levels decrease with increasing leaf age.
Bacterial wilt, caused by numerous species of the genera Corynebacterium, Erwinia, Pseudomonas, and Xanthomonas, induces stunting, wilting, and withering, starting usually with younger leaves.
The presence of young developing leaves often accelerates the aging of older leaves; removal of the younger leaves retards the senescence of the older ones, suggesting control by competition for nutrients.
Within 4 days, invertase levels in the plants shot up 15 times, and younger leaves thickened, curled, and yellowed.
Comparison of attachment to leaves of different ages showed that Salmonella displayed higher affinity to older compared to younger leaves (1.5 log).
Submergence promoted chlorosis in both rice lines although older leaves lost more chlorophyll in 'FR13A' and younger leaves lost more in 'TL3'TL3
Further studies showed that REL2 protein is mainly distributed along the plasma membrane of cells and the REL2 gene is relatively higher expressed in younger leaves of rice.
Relative to WT, the d10 mutant had a higher N concentration in older leaves but a lower N concentration in younger leaves, while the d3 mutant showed a considerably lower N concentration, especially in its younger leaves under normal N levels.
Water stress-induced decrease in total plant leaf area due to a combination of limited expansion of younger leaves and shedding of old leaves caused the leaf area ratio reduction under drought.
To do so, one to two older and three younger leaves than the reference senescing leaf (rank 0) from Aviso and Express plants grown under optimal and sub-optimal nitrogen fertilization were analyzed.
Such variations may be due to different stages of harvesting as younger leaves prior to flowering may contain more protein than mature leaves and leaves after flowering (Nedorizescu, 1972).
