Changes in chlorophyll contents during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the chlorophyll contents (SPAD unit) at −3 d (100% chlorophyll content = 41.5 for XLZ13 and 44.0 for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Appearance of Alternaria disease on cotton leaves pre-treated by various durations of chilling stress at 16/12°C.

<p>Various durations of chilling stress pre-treatments were performed at 16/12°C. Then the pre-treated cotton leaves were inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1 by slightly brushing method and returned to grow at optimal temperature of 28/20°C. The mock inoculations were performed with sterilized water. Presented pictures photographed at 15 days after inoculation.</p

Influences of chilling stress pre-treatments performed with various durations of chilling stress at 16/12°C on occurrence and development of Alternaria disease.

<p>Cotton seedlings were pre-treated with various duration of chilling stress at 16/12°C, then inoculated with <i>A. alternata</i> isolate A1, and removed to grow at optimal temperature of 28/20°C; Different letters behind the disease index indicate significant difference with the <i>P</i> value of 0.05. The first letters indicate the comparison among various duration of chilling stress at 16/12°C and the second letters indicate the comparison between XLZ13 and XLZ33.</p

Changes in soluble protein contents during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the soluble protein content at −3 d (100% soluble protein content = 24.8 mg/gFW for XLZ13 and 27.5 mg/gFW for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Changes in MDA content during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the malondialdehyde contents at −3 d (100% MDA content = 22.4 nmol/gFW for XLZ13 and 21.8 nmol/gFW for XLZ33 leaves, respectively). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Changes in electrolyte leakage during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b,c,d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values of membrane electrolyte leakage. The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Influences of chilling stress pre-treatments performed with various low temperatures on occurrence and development of Alternaria disease.

<p>Cotton seedlings were pre-treated with chilling stress for 3 days, then inoculated with <i>A. alternata</i> isolate A1, and removed to grow at optimal temperature of 28/20°C; Different letters behind the disease index indicate significant difference with the <i>P</i> value of 0.05. The first letters indicate the comparison among different temperatures of chilling stress pre-treatment and the second letters indicate the comparison between XLZ13 and XLZ33.</p

Changes in Fv/Fm ratio during Alternaria disease development promoted by chilling stress pre-treatment.

<p>a: the control cotton plants sustained growing at optimal temperature of 28/20°C. b, c, d: Cotton plants performed with chilling stress pre-treatments at 20/16°C, 16/12°C, 12/8°C for 3 days respectively, then inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1, and returned to grow at 28/20°C. All collected data (mean ± standard deviation SD with 6 replicates) were presented as relative values to the maximal quantum yield of photosystem II photochemistry (Fv/Fm ratio) at −3 d (100% Fv/Fm ratio = 0.805 for XLZ13 and 0.812 for XLZ33 leaves). The chilling stress pre-treatment period was indicated by time points from −3 to 0, and the period after inoculation was indicated by time points from 0 to 15.</p

Appearance of Alternaria disease on cotton leaves pre-treated by chilling stress with various low temperatures.

<p>Chilling stress pre-treatments were performed with various low temperatures for 3 days. Then the pre- treated cotton leaves were inoculated with 1.2×10⁴ conidial/mL inoculum suspension of <i>A. alternata</i> isolate A1 by slightly brushing method and returned to grow at optimal temperature of 28/20°C. The mock inoculations were performed with sterilized water. Presented pictures photographed at 15 days after inoculation.</p