Histological sections of the 4S wheat.

<p><b>A.</b> The lateral meristem of the axillary bud at the axil of the flag leaf. <b>B.</b> Featuring the branding stem from the axillary bud at the axil of the flag leaf shown in Fig 2A. <b>C.</b> The spike axis of the 4S wheat. <b>D.</b> The spike axis of 2174 wheat. VB: vascular bundle; PPC: pith parenchymal cell; PC: parenchymal cell.</p

Morphological characteristics of the 4S wheat plant.

<p><b>A.</b> A normal plant with one spike on one stem. <b>B.</b> A 4S wheat plant. The part to be featured is indicated with a white line. <b>C.</b> Tillers from the axillary buds at the axil of each of three aerial leaves on the elongated internodes. <b>D.</b> An axillary bud at the axil of the flag leaf on the elongated internodes developed directly to a spike is indicated by an arrow in red, and a spikelet meristem advanced to a spike is indicated by an arrow in blue. <b>E.</b> The spike developed from the axil of the flag leaf on the elongated internodes in Fig 1D is exposed after the flag leaf is removed. <b>F.</b> The developing spikes or tillers from the axils of three leaves on the elongated internodes are exposed and indicated by arrows in purple after the aerial leaves are removed. <b>G.</b> Supernumerary spikelets developed from on rachis node are squared in red line. <b>H.</b> The two spikelets on the same rachis node are featured to show that the normal spikelet indicated by a white arrow and the supernumerary spikelet indicated by a yellow arrow reside on the same rachis node. <b>I.</b> A stem with branching shoot. The numbers indicate grains per spike. <b>J.</b> A spike with branching spikes with normal fertility. The numbers indicate grains per spike. <b>K.</b> The seeds from the supernumerary spikes are normal (on the left), and the 2174 seed are shown on the right.</p

Changes in soluble sugar content of the leaf, leaf sheath, and internode of sequential and non-sequential senescence wheat cultivars under natural and drought conditions.

<p>(A) Flag leaf, (B) The second leaf, (C) Flag leaf sheath, (D) The second leaf sheath, (E) Peduncle, (F) Penultimate internode. Solid and dash lines represent natural and drought conditions. Each bar represents the mean ± SD of three replications. Asterisks indicate statistically significant difference between sequential and non-sequential senescence wheat cultivars in the same conditions (*<i>P</i> ≤ 0.05, ** <i>P</i> ≤ 0.01).</p

Differences in Sugar Accumulation and Mobilization between Sequential and Non-Sequential Senescence Wheat Cultivars under Natural and Drought Conditions

<div><p>Wheat leaf non-sequential senescence at the late grain-filling stage involves the early senescence of younger flag leaves compared to that observed in older second leaves. On the other hand, sequential senescence involves leaf senescence that follows an age-related pattern, in which flag leaves are the latest to undergo senescence. The characteristics of sugar metabolism in two sequential senescence cultivars and two non-sequential senescence cultivars under both natural and drought conditions were studied to elucidate the underlying mechanism of drought tolerance in two different senescence modes. The results showed that compared to sequential senescence wheat cultivars, under natural and drought conditions, non-sequential senescence wheat cultivars showed a higher leaf net photosynthetic rate, higher soluble sugar levels in leaves, leaf sheaths, and internodes, higher leaf sucrose synthase (SS) and sucrose phosphate synthase (SPS) activity, and higher grain SS activity, thereby suggesting that non-sequential senescence wheat cultivars had stronger source activity. Spike weight, grain weight per spike, and 100-grain weight of non-sequential senescence cultivars at maturity were significantly higher than those of sequential senescence cultivars under both natural and drought conditions. These findings indicate that the higher rate of accumulation and the higher mobilization of soluble sugar in the leaves, leaf sheaths and internodes of non-sequential senescence cultivars improve grain weight and drought tolerance. At the late grain-filling stage, drought conditions adversely affected leaf chlorophyll content, net photosynthetic rate, soluble sugar and sucrose content, SS and SPS activity, gain SS activity, and weight. This study showed that higher rates of soluble sugar accumulation in the source was one of the reasons of triggering leaf non-sequential senescence, and higher rates of soluble sugar mobilization during leaf non-sequential senescence promoted high and stable wheat yield and drought tolerance.</p></div

Changes in chlorophyll content of flag leaf and the second leaf of sequential and non-sequential senescence wheat cultivars under natural and drought conditions.

<p>(A) Xinong 88, sequential senescence wheat cultivar. (B) NR9405, sequential senescence wheat cultivar. (C) Wenmai 19, non-sequential senescence wheat cultivar. (D) Lankaoaizao 8, non-sequential senescence wheat cultivar. Solid and dash lines represent natural and drought conditions. Each bar represents the mean ± SD of three replications. Asterisks indicate statistically significant difference between flag leaf and the second leaf in the same conditions (*<i>P</i> ≤ 0.05, ** <i>P</i> ≤ 0.01).</p

Changes in leaf sucrose content, SS and SPS activities of sequential and non-sequential senescence wheat cultivars under natural and drought conditions.

<p>(A), (C) and (E) Flag leaf. (B), (D) and (F) The second leaf. Solid and dash lines represent natural and drought conditions. Each bar represents the mean ± SD of three replications. Asterisks indicate statistically significant difference between sequential and non-sequential senescence wheat cultivars in the same conditions (*<i>P</i> ≤ 0.05, ** <i>P</i> ≤ 0.01).</p

Changes in net photosynthetic rate of flag leaf and the second leaf of sequential and non-sequential senescence wheat cultivars under natural and drought conditions.

<p>(A) Flag leaf, (B) The second leaf. Solid and dash lines represent natural and drought conditions. Each bar represents the mean ± SD of nine replications. Asterisks indicate statistically significant difference between sequential and non-sequential senescence wheat cultivars in the same conditions (*<i>P</i> ≤ 0.05, ** <i>P</i> ≤ 0.01).</p

Spike weight, grain weight per spike, 100-grain weight, and grain SS activities (cleavage direction) of sequential and non-sequential senescence wheat cultivars under natural and drought conditions.

<p>(A) The increased weight in spike and grain per spike from 0 to 20 days after anthesis (DAA) and 20 to 40 DAA (maturity), (B) Spike weight, grain weight per spike, and 100-grain weight at maturity, (C) grain SS activities (cleavage direction). Solid and dash lines represent natural and drought conditions. Each bar represents the mean ± SD of three replicates. Different letters indicate significant difference (<i>P</i> ≤ 0.05) between two treatments and among four cultivars. Asterisks indicate significant difference between sequential and non-sequential senescence wheat cultivars in the same conditions (*<i>P</i> ≤ 0.05, ** <i>P</i> ≤ 0.01).</p

EC₅₀ values of the compounds with higher initial activity against four strains of fungi.

<p>EC₅₀ values of the compounds with higher initial activity against four strains of fungi.</p

Bioactivity and structure-activity relationship of cinnamic acid esters and their derivatives as potential antifungal agents for plant protection

<div><p>A series of cinnamic acid esters and their derivatives were synthesized and evaluated for antifungal activities in vitro against four plant pathogenic fungi by using the mycelium growth rate method. Structure−activity relationship was derived also. Almost all of the compounds showed some inhibition activity on each of the fungi at 0.5 mM. Eight compounds showed the higher average activity with average EC₅₀ values of 17.4–28.6 μg/mL for the fungi than kresoxim-methyl, a commercial fungicide standard, and ten compounds were much more active than commercial fungicide standards carbendazim against <i>P</i>. <i>grisea</i> or kresoxim-methyl against both <i>P</i>. <i>grisea</i> and <i>Valsa mali</i>. Compounds <b>C1</b> and <b>C2</b> showed the higher activity with average EC₅₀ values of 17.4 and 18.5 μg/mL and great potential for development of new plant antifungal agents. The structure−activity relationship analysis showed that both the substitution pattern of the phenyl ring and the alkyl group in the alcohol moiety significantly influences the activity. There exists complexly comprehensive effect between the substituents on the phenyl ring and the alkyl group in the alcohol moiety on the activity. Thus, cinnamic acid esters showed great potential the development of new antifungal agents for plant protection due to high activity, natural compounds or natural compound framework, simple structure, easy preparation, low-cost and environmentally friendly.</p></div